var lunar = {
	tg: '甲乙丙丁戊己庚辛壬癸',
	dz: '子丑寅卯辰巳午未申酉戌亥',
	number: '一二三四五六七八九十',
	year: '鼠牛虎兔龙蛇马羊猴鸡狗猪',
	month: '正二三四五六七八九十冬腊',
	monthadd: [0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334],
	calendar: [0xA4B, 0x5164B, 0x6A5, 0x6D4, 0x415B5, 0x2B6, 0x957, 0x2092F, 0x497, 0x60C96, 0xD4A, 0xEA5, 0x50DA9,
		0x5AD, 0x2B6, 0x3126E, 0x92E, 0x7192D, 0xC95, 0xD4A, 0x61B4A, 0xB55, 0x56A, 0x4155B, 0x25D, 0x92D,
		0x2192B, 0xA95, 0x71695, 0x6CA, 0xB55, 0x50AB5, 0x4DA, 0xA5B, 0x30A57, 0x52B, 0x8152A, 0xE95, 0x6AA,
		0x615AA, 0xAB5, 0x4B6, 0x414AE, 0xA57, 0x526, 0x31D26, 0xD95, 0x70B55, 0x56A, 0x96D, 0x5095D, 0x4AD,
		0xA4D, 0x41A4D, 0xD25, 0x81AA5, 0xB54, 0xB6A, 0x612DA, 0x95B, 0x49B, 0x41497, 0xA4B, 0xA164B, 0x6A5,
		0x6D4, 0x615B4, 0xAB6, 0x957, 0x5092F, 0x497, 0x64B, 0x30D4A, 0xEA5, 0x80D65, 0x5AC, 0xAB6, 0x5126D,
		0x92E, 0xC96, 0x41A95, 0xD4A, 0xDA5, 0x20B55, 0x56A, 0x7155B, 0x25D, 0x92D, 0x5192B, 0xA95, 0xB4A,
		0x416AA, 0xAD5, 0x90AB5, 0x4BA, 0xA5B, 0x60A57, 0x52B, 0xA93, 0x40E95
	]
}

function getLunarDate(date) {

	var year, month, day;
	if (!date) {
		date = new Date(), year = date.getFullYear(), month = date.getMonth(), day = date.getDate();
	} else {
		date = date.split('-'), year = parseInt(date[0]), month = date[1] - 1, day = parseInt(date[2]);
	}

	if (year < 1921 || year > 2030) {
		return {}
	}

	var total, m, n, k, bit, lunarYear, lunarMonth, lunarDay;
	var isEnd = false;
	var tmp = year;
	if (tmp < 1900) {
		tmp += 1900;
	}
	total = (tmp - 1921) * 365 + Math.floor((tmp - 1921) / 4) + lunar.monthadd[month] + day - 38;
	if (year % 4 == 0 && month > 1) {
		total++;
	}
	for (m = 0;; m++) {
		k = (lunar.calendar[m] < 0xfff) ? 11 : 12;
		for (n = k; n >= 0; n--) {
			bit = (lunar.calendar[m] >> n) & 1;
			if (total <= 29 + bit) {
				isEnd = true;
				break;
			}
			total = total - 29 - bit;
		}
		if (isEnd) break;
	}
	lunarYear = 1921 + m;
	lunarMonth = k - n + 1;
	lunarDay = total;
	if (k == 12) {
		if (lunarMonth == Math.floor(lunar.calendar[m] / 0x10000) + 1) {
			lunarMonth = 1 - lunarMonth;
		}
		if (lunarMonth > Math.floor(lunar.calendar[m] / 0x10000) + 1) {
			lunarMonth--;
		}
	}

	return {
		lunarYear: lunarYear,
		lunarMonth: lunarMonth,
		lunarDay: lunarDay,
	};
}


function getLunarDateString(lunarDate) {
	if (!lunarDate.lunarDay) return;
	var data = {},
		lunarYear = lunarDate.lunarYear,
		lunarMonth = lunarDate.lunarMonth,
		lunarDay = lunarDate.lunarDay;

	data.tg = lunar.tg.charAt((lunarYear - 4) % 10);
	data.dz = lunar.dz.charAt((lunarYear - 4) % 12);
	data.year = lunar.year.charAt((lunarYear - 4) % 12);
	data.month = lunarMonth < 1 ? '(闰)' + lunar.month.charAt(-lunarMonth - 1) : lunar.month.charAt(lunarMonth - 1);

	data.day = (lunarDay < 11) ? "初" : ((lunarDay < 20) ? "十" : ((lunarDay < 30) ? "廿" : "三十"));
	if (lunarDay % 10 != 0 || lunarDay == 10) {
		data.day += lunar.number.charAt((lunarDay - 1) % 10);
	}

	return data;
}

// export default {
// 	getLunarDate : getLunarDate('2018-7-19'),
// 	getLunarDateString : getLunarDateString("")
// }

module.exports = {
    getLunarDate,
    getLunarDateString
}
